Maximum and minimum thermometer

ABSTRACT

A maximum and minimum registering thermometer presents maximum and minimum readings as numbers on movable scales. The scales are on arcuate scale elements comprising nesting, spoked annular elements rotated through one-way and other-way couplings, by the thermometric pointer.

1451 Mar. 12, 1974 United States Patent [191 Howard 'l'ollcfscn ctFOREIGN PATENTS OR APPLICATIONS n T E MM UO n m m xm m AH v MTl 4 .M 1 U255,835 9/1926 Great Britain [73] Assignee: Sybron Corporation,Rochester,

' Primary ExaminerRichard C. Queisser Apr. 24, 1972 AssistantExaminerDaniel M. Yasich Appl. No.: 246,802

[22] Filed:

Attorney, Agent, or Firm-Theodore B. Roesselj Joseph C. MacKenzie 4 Wm25 Hk m0 6 m 3 M d 1 G 0 m UI H1 1 55 [58] Field of Search..... 73/363];116/129 A, 129 B A maximum and minimum registering thermometer presentsmaximum and minimum readings as numbers on movable scales. The scalesare on arcuate scale ele- References Cited UNITED STATES PATENTS mentscomprising nesting, spoked annular elements rotated through one-way andother-way couplings, by the thermometric pointer.

2 605,736 8/1952 Cook et a1 116/129 B 2,278,145 3/1942 Milestone at211...... 116/129 T 6 Claims, 4 Drawing Figures PATENIE-flm 12 m4 SHEET2 UP 2 a FIG. 4

1 MAXIMUM AND MINIMUM THERMOMETER BACKGROUND OF THE INVENTION The priorart discloses instruments for indicating current and past values ofvarious conditions, such as temperature, barometric pressure, and soforth. The past values are maxima and minima of the condition, and areread on the same scale as the current value, usually by means ofpointers.

SUMMARY OF THE PRESENT INVENTION BRIEF DESCRIPTION OF THE DRAWINGS FIG.1 shows a thermometer according to the invention in a partial sectionalview wherein proportions are exaggerated for clarity of description;

FIG. 2 shows a plan view of a thermometer according to the invention;FIG. 2A being a fragmentary view of the device of FIG. 2, similar to theview of FIG. 1; and

FIGS. 3 and 4 are respective plan and diametral sectional views of adetail of the invention, as embodied in practice,

In FIG. 1, a casing 1 has a right-cylindrical post 2 fixed at its leftend to the casing. A bimetallic spiral coil 3 has its inner end 4 fixedto the post 2 and its outer end 5 fixed to a pointer'6. Pointer 6 has anindex portion 7, and a hub portion 8, this last journaling the pointer 6on the post for rotation on an axis which is the axis of the post. Thisis a typical known arrangement of pointer, coil, post and casing, andhas the usual result that, as the temperature of the coil changes, thepointer is rotated to various positions in a vertical plane normal tothe plane of the Figure. In FIG. 1, said vertical plane is defined by ascale plate 9 fixed to a transparent cover 10 forming part of easing 1.Accordingly, an arcuate scale (not shown), on plate 9, and centered onthe axis of rotation of pointer 6, can be used to define the variouspositions of index portion 7, in terms of temperature of coil 3.

Arcuate scale elements 11 and 12 have respective spokes 13 and 14, whichterminate in respective hub portions 15 and 16. The hub portions providefor journalling scale elements 11 and 12 on post 2, analagous to thejournalling of pointer 6 onpost 2. Elements 1] and 12 are separated by aWasher 17, and in turn collectively separate a pair of washers l8 and19.

As shown, the several hub-portions and washers are spaced from oneanother and from the post. This is merely for clarity in illustration.In practice, the hubportions will fit the post substantially precisely,with hub portions 15 and 16, and washers l7, l8 and 19 more or less infrictional engagement with each other. Preferably, Washer 17 is apermanent magnet, and hub portions 15 and 16 are made of ferromagneticmaterial. Washer 17 is fixed to the post 2, so will draw the hubportions15 and 16 to it. Washers 18 and 19 act as retainers for the hub portionsand are fixed to the post at points providing a spacing from washer 17 alittle greater than the thickness of the hub portions 15 and 16. Also,washer 18 will be spaced from hub portion 8.

It is to be observed that the foregoing arrangement of hub portions andwashers is one of a number of known conventional arrangements forproviding substantially frictionless rotation of hub portion 8 on post2, while introducing a controlled amount of friction for allowing hubportions 15 and 16 to be rotated substantially freely, yet to remaincapable of staying in any given rotary position, by virtue of thefriction alone between them and magnet 17.

Pointer 6 is provided with lugs 21 and 22 which respectively form partof a one-way coupling to scale element 11 and part of an other -waycoupling to scale element 12. By one-way coupling, I mean that if thecoil temperature increases, and its winding and construction is, say,such as to rotate pointer 6 into the Figure,

then lug 21 will strike spoke l3 and rotate scale element 11. Byother-way coupling," therefore, I would mean that if the coiltemperature decreased enough, the lug 22 would move out of the paper,and strike a lug 20 fixed to the hub portion 16 and rotate scale element12. It is to be observed that using the separate lug 20, rather thanspoke 14, as part of the other-way coupling, is merely exemplary of amechanical refinement. Conversely, it is to be noted that if the lug 21were a little longer, it would provide, with spoke 14, the other-waycoupling, as well as the one-way coupling it forms, with spoke 13. Whatthe Figure actually shows, as to the couplings, reflects the designconsiderations that were found convenient in fabricating actual examplesof the instrument.

The use and function of the above structure is that typical of maximumand minimum registering thermometers. Thus, as coil 3 winds and unwindsin response to corresponding temperature fluctuations, pointer 6 rotatesone way or another in correspondence with such fluctuations. Scaleelement 11, however, goes only one-way, and stays were it is put, so tospeak, whereas scale element 12 goes only the other way, but also stayswhere it is put. Thus, if one looks at the instrument from the right,one sees index portion 7, the

position of which can be read in terms of a scale (not 7 shown) on plate9. At the same time, one sees, through a window 23 in plate 9, numbersof the scales (not shown) on scale elements 11 and 12, which numbersread in terms of the highest and lowest temperatures attained by coil 3,up to the time of reading.

Aresetting knob 24 is also provided, as is customary, for resetting thescale elements 11 and 12 from time to time, in order to be able to getsome idea of when the maximum and minimum temperatures occurred. Knob 24has fixed thereto a post 25 journaled in the scale plate and normallyheld, by a spring 26, in the position shown. Affixed to the end of post25 is a lug 27. The operation of these elements is conventional: toreset, the knob 24 is turned to a position wherein one of the spokes 13and 14 are between lug 27 and pointer 6, whereupon the knob is pushed inand rotated so that lug 27 picks up the spoke and moves it until thecorresponding one of lugs 21 and 22 is contacted. The knob is thenreleased, and the operation is repeated for the other of lugs 21 and 22.In the end, the numbers visible in window 23 will be those correspondingto the position of index portion 7. Thereafter, the instrument is a leftto its own devices and the vagaries of temperature, until such time asit is desired to reset the scale elements 11 and 12.

FIG. 2 exemplifies one indicating configuration based on the principlesof FIG. 1. Thus, there is a temperature scale 50, visible in full,running from a minimum of about -40 F to a maximum of about 120 F.Partially shown are scales 51 and 52, which are on scale elements 11 and12, respectively. The divisions and numbers of 51 and 52 are, however,the same as those of scale 50. As is evident from the Figure, scale 51indicates maximum temperature and scale 52 indicates minimumtemperature.

Windows 53 and 54, corresponding to the single window 23 in FIG. 1, andhaving index lines 55 and 56, provide for reading the scales 51 and 52at the index lines. The windows are in a mask 57 which conceals thestructure behind it, except for the index portion 7 of pointer 6, theposition of which can therefore be read off on scale 50. The knob 24 mayhave an arrow 58 thereon which shows the angular position of the lug 27,in spite of this last being concealed by mask 57.

Mask 57 and scale 50, conveniently, may be printed on the cover glass10. Supposing no structural or dimensional change in the mechanism, thiswould amount to putting the scale on cover glass 10 around the peripheryof plate 9, rather than on it, and to rotating window 23, 180 from theposition shown in FIG. 1. Actually, as will be seen from FIG. 2A, mask57 (shown with some thickness for illustration purposes) is in essence aslightly smaller version of plate 9, whereas case 1 and cover glass 10are slightly enlarged, as compared to FIG. 1.

It will be observed that the mask 57 for the most part conceals thecontents of casing 1. On the other hand, it serves to contrast andintensify the maximum and minimum readings, giving somewhat of a digitaleffect, so to speak, due to the fact that not much of scales 51 and 52is visible except a number or two, close in value to the actual reading.Obviously, this effect may be intensified by dimensioning the angularextent of the windows 53 and 54 so that not more than one full numbercan be seen at a time, but at least one full number is always visible.Again, the windows 53 and 54 could be located on opposite sides of knob24.

Preferably, the'scale elements 11 and 12 are 0.010 inch stainless steelstampings, such as is shown in FIGS. 3 and 4, in the case of element120, which corresponds to element 12 of FIG. 1.

Element 120 is essentially an annulus 59, having a spoke 140, a hubportion l60, and a lug 200, corresponding to the like-entitled parts 14,16, and of element 12. In addition, there is also a spoke 141. Not shownare strengthening ribs, upsets, and the like which are preferablyembossed in the spokes and annulus for improving their rigidity. Acounterpart of element 11 would be quite similar, except to lack thecounterpart of lug 200.

The second spoke is provided only for added rigidity. The lesser angularspacing between two spokes is relatively limited since the amount ofrotation contemplated is nearly full circle. Functionally, what isrequired is a certain amount of empty space for the lugs 21 and 22 tomove in freely except when driving the re spective scale elements. FIGS.3 and 4, which are about l 9% times life-size, and to scale, represent adesign for 4 maximizing that empty space while obtaining lightness andcompactness of the scale element arrangement. Apart from these things,however, the two scale elements are in essence coaxially mounted dialsunequal in radius and having sectors cut out to allow for oneway andother-way" coupling.

It will be evident from the foregoing that various modifications may bemade in the mechanism of the thermometer, without departing from theinvention. The instrument shown stems from a design for measuringambient air temperature (so perforations, not shown, may be made incasing l, for circulation of ambient air inside the casing). However,the illustrated arrangement would be suitable for any type of instrumentfor indicating both current and past values of one condition or another.

The claims appended hereto contemplate an instrument which will indicateboth maxima and minima. However, it is within the scope of the inventionto provide for just one or the other thereof, alone.

Having described my invention in accordance with the statutes,

I claim:

1. A maximum and minimum registering device, comprising, in combination,

a first indicator, a second indicator, a third indicator, all said threeindicators journalled on a post in said registering device, and a sensorresponsive to a condition and connected to said first indicator forcausing said first indicator to indicate the value of said condition;

said second indicator having a one-way, detachable coupling selectivelycoupled to said first indicator and being frictionally retained on saidpost for indicating maximum values of said condition, and said thirdindicator having an other-way detachable coupling selectively coupled tosaid first indicator and being frictionally retained on said post forindicating minimum values of said condition;

said second indicator being a first arcuate scale element having a firstscale of numbers thereon, said third indicator being a second arcuatescale element having a second scale of numbers thereon;

said device also including a plate fixed on the interior of a crystal ofsaid registering device with respect to and overlying said scales, andhaving a first window therein through which is visible at least onenumber of said first scale, said plate also having a second windowtherein through which is visible at least one number of said secondscale.

said one-way detachable coupling providing for moving said first arcuatescale element past said first window for presenting its said numbers toview therethrough, substantially one by one upon movement of said firstindicator in one direction, and said other-way detachable couplingproviding for moving said second arcuate scale element past said secondwindow for presenting its said numbers to view therethrough,substantially one by one upon movement of said first indicator in theopposited direction.

2. The invention of claim 1, wherein said condition is temperature.

3. The invention of claim 1, wherein said plate conceals said scales,except insofar as said scales are visible through said windows, andwherein the angular extent of each said window is approximately justlarge enough mounting it for rotation about said axis, one of saidspokes overlying the other along the direction of said axis;

said first indicator having lug means projecting along the direction ofsaid axis so far as to contact either said spoke upon rotation of saidfirst indicator. 6. The invention of claim 5, wherein said condition istemperature.

1. A maximum and minimum registering device, comprising, in combination,a first indicator, a second indicator, a third indicator, all said threeindicators journalled on a post in said registering device, and a sensorresponsive to a condition and connected to said first indicator forcausing said first indicator to indicate the value of said condition;said second indicator having a one-way, detachable coupling selectivelycoupled to said first indicator and being frictionally retained on saidpost for indicating maximum values of said condition, and said thirdindicator having an other-way detachable coupling selectively coupled tosaid first indicator and being frictionally retained on said post forindicating minimum values of said condition; said second indicator beinga first arcuate scale element having a first scale of numbers thereon,said third indicator being a second arcuate scale element having asecond scale of numbers thereon; said device also including a platefixed on the interior of a crystal of said registering device withrespect to and overlying said scales, and having a first window thereinthrough which is visible at least one number of said first scale, saidplate also having a second window therein through which is visible atleast one number of said second scale. said one-way detachable couplingproviding for moving said first arcuate scale element past said firstwindow for presenting its said numbers to view therethrough,substantially one by one upon movement of said first indicator in onedirection, and said other-way detachable coupling providing for movingsaid second arcuate scale element past said second window for presentingits said numbers to view therethrough, substantially one by one uponmovement of said first indicator in the opposited direction.
 2. Theinvention of claim 1, wherein said condition is temperature.
 3. Theinvention of claim 1, wherein said plate conceals said scales, exceptinsofar as said scales are visible through said windows, and wherein theangular extent of each said window is approximately just large enoughthat only a minor part of the corresponding said scale is visibletherethrough.
 4. The invention of claim 3 wherein said condition istemperature.
 5. The invention of claim 1, wherein said indicators arerotary and mounted for rotation about a common axis, said first arcuatescale element having a first radial spoke mounting it for rotation aboutsaid axis, said second arcuate scale element having a second radialspoke mounting it for rotation about said axis, one of said spokesoverlying the other along the direction of said axis; said firstindicator having lug means projecting along the direction of said axisso far as to contact either said spoke upon rotation of said firstindicator.
 6. The invention of claim 5, wherein said condition istemperature.